ABSTRAK
Ketersediaan air semakin sulit karena penduduk terus bertambah sedangkan sumber daya air tetap. Kabupaten Lebak merupakan wilayah dengan rezim hujan barat yang memiliki iklim lebih basah dari pantai timur di Pulau Jawa, serta potensi sumber daya air yang cukup banyak. Sulit air terjadi pada musim kemarau panjang. Awal musim kemarau dan awal musim hujan ditentukan dengan metode De Boer. Digunakan data curah hujan periode 30 tahun (1986 – 2015) dengan 13 titik stasiun. Pola spasial wilayah sulit air didapat dari overlay antara interpolasi durasi musim kemarau rata-rata dan tingkat kekeringan rata-rata. Variabel jenis batuan, jenis tanah, ketinggian, dan lereng digunakan untuk mengetahui dominasi karakter fisik dari wilayah sulit air. Pola spasial wilayah sulit air rata-rata tahunan dibandingkan dengan pola tahun 2015. Hasil penelitian menunjukkan pola spasial wilayah sulit air di Kabupaten Lebak semakin ke utara dan selatan semakin tinggi. Wilayah ini didominasi oleh jenis batuan endapan tersier, jenis tanah latosol, wilayah ketinggian 0 – 100 mdpl, dan kelerengan landai (< 8%). Durasi musim kemarau dan tingkat kekeringan tahun 2015 dari rata-rata tahunan menunjukkan pola yang berbeda. Desa-desa yang mengalami sulit air tahun 2015 cenderung akibat penyimpangan tingkat kekeringan yang tinggi.

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ABSTRACT
Water availability becomes more difficult due to the population growth while the source of water remains constant. Lebak is a region with western rain regime that has a wetter climate of the east coast of Java, as well as the potential of water resources is quite a lot. Water scarcity occurs during the dry season. The beginning of the dry season and the beginning of rainy season is determined by the method of De Boer. Rainfall data used a period of 30 years (1986 – 2015) with 13 stations. Spatial pattern of water scarcity area is obtained by performing overlay between the interpolation of dry season duration average and the interpolation of dryness level average. Rock types, soil types, elevation, and slope are used to determine the dominance of the physical character of water scarcity area. The spatial pattern of water scarcity area annual average is compared to the pattern in 2015. The results showed the spatial pattern of water scarcity area in Lebak more to the north and the south is getting higher. The area is dominated by tertiary sedimentary rocks, latosol soil type, elevation area of 0 – 100 meters above sea level, and slope ramps (< 8%). The duration of the dry season and dryness level in 2015 showed different pattern compared to the annual average. The villages that were affected by water scarcity in 2015 are likely due to high irregularities of dryness level.